Contrast-to-noise ratio in functional MRI of relative cerebral blood volume with sprodiamide injection.

The purpose of this study was to investigate the dependence of contrast-to-noise ratio (CNR) on the dose and rate of sprodiamide injection in magnetic resonance relative cerebral blood volume [rCBV] imaging, rCBV maps for 35 normal volunteers were constructed from dynamic MR image sets acquired with echo-planar spin-echo imaging after intravenous injection of sprodiamide, Doses of .1, .2, and .3 mmol/kg, at rates of 2 ml/second and 5 ml/second, were tested, CNRs and blood/volume ratios of gray to white matter were computed, CNR depended on dose [P <.0001] but was independent of injection rate [P <.69). rCBV ratios of gray to white matter were dose independent (P <.38) and rate independent (P <.97), The dependence of CNR on dose, but not injection rate, has practical implications in optimal protocol design, The independence of gray/white ratios supports the theory underlying the generation of rCBV maps.